diff --git a/plugins/ps/functions b/plugins/ps/functions
index 3e7aaac3b66..7321d6633bd 100755
--- a/plugins/ps/functions
+++ b/plugins/ps/functions
@@ -10,7 +10,7 @@ print_dokku_scale_file() {
 }
 
 generate_scale_file() {
-  local APP="$1"; local IMAGE_TAG="$3"; local IMAGE=$(get_app_image_name $APP $IMAGE_TAG); local DOKKU_SCALE_FILE="$DOKKU_ROOT/$APP/DOKKU_SCALE"
+  local APP="$1"; local IMAGE_TAG="$2"; local IMAGE=$(get_app_image_name $APP $IMAGE_TAG); local DOKKU_SCALE_FILE="$DOKKU_ROOT/$APP/DOKKU_SCALE"
   verify_app_name "$APP"
 
   copy_from_image "$IMAGE" "/app/DOKKU_SCALE" "$DOKKU_ROOT/$APP" 2>/dev/null || true